Selective message register system



A ril 26, 1949.

J. W. DEHN ET AL SELECTIVE MESSAGE REGISTER SYSTEM Filed July l, 1947 IN VE N TOPS .4 w DEHN n4 WHITNEY ATTORNEK Patented Apr. 26, 1949 UNITED ATENT QFFICE Joseph W. Dehn,

Whitney, Madison,

Great Neck, N. Y., and Wiley N. 5., assignors to Bell Telephone Laboratories, Incorporated, New York, N. 1., a corporation of New York Application July 1, 1947, Serial No. 758,308

Claims.

This invention relates to telephone systems and more particularity to systems comprising socalled message rate party lines.

An object of the invention is to automatically operate a counting device or register, individual to a calling station, when a connection is established with the line of the called station and the call is answered.

In exchange areas where message rate service is generally furnished the central office switching equipment is usually equipped with circuit means, responsive to the establishment of a connection with and the response of a called subscriber, to operate a so-called message register individual to the calling station which means usually comprises two or more extra conductors inthe exchange wiring in addition to the usual tip, ring and sleeve conductors.

In some isolated central ofiices, however, most of the lines are what are termed flat rate lines that is, no charge is made for local calls, and as no message registers are provided, no extra register conductors are required. It occasionally happens, however, that there are a few message rate and prepayment coin box lines to be served by the same switching equipment and the present invention relates to the provision of call charging facilities whereby selective operation of a message register, or the collect or return of a coin at a pay station, can be controlled over the sleeve conductor of the line without adding extra conductors in the exchange wiring.

A feature of the invention resides in an arrangement for selectively operating either of two message registers or either of the collect and return magnets of a coin box, over the sleeve conductor of the line by selectively connecting to the sleeve conductor, when the called station answers, positive potential direct current impulses derived from either the positive or negative half of an alternating current wave. The two message registers, or the coin box magnets, are connected to the sleeve each in series with a gasfilled discharge tube which tubes are alternately ionized and conditioned for discharge in accordance with the phase changes of the same alternating current wave. One or the other of the registers, or coin box magnets will be operated, depending on which series of impulses are connected to the sleeve at the time registration or coin control is to be effected. If impulse-s derived from the positive half Wave of the supply source are connected to the sleeve the gas tube which is primed during the same half cycle will break down and operate its associated register, and,

conversely, if impulses derived from the negative half wave of the supply source are applied to the sleeve the other tube which is ionized at the same time will fire and operate the other register.

The arrangement of the invention wherein the foregoing features are incorporated will be under. stood from the following description, the drawing of which shows a two-party message rate subscribers line L serving two subscribers sta= tions PI and P2. Line L terminates in the bank of a line finder switch LF. A message rate trunk MRT connects the wipers of the line finder LE to the wipers of a selector SI, and a connector switch C2 completes the connection to a called line LX terminating at a subscribers station X.

Subscribers stations PI and P2 connected to the line L differ from each other only in that while the removal of the receiver at station P2 connects both conductors of the line L to ground, through the station ringer, the same operation of the receiver switchhook at station PI is not effective to establish such a ground connection, which difierenceenables identification of the call.- ing station on each call initiated over the line L.

Line circuit LC comprises the usual line relay 30, a cutoff relay 35, two message registers MRI and MR2, one for each of the stations PI and P2, two message register control relays MRGI and MRCZ and the two three-element cold oath, ode gas-filled tubes I and 2, each of which when conducting causes operation of either MRCI .or MRC2 to actuate the corresponding register MRI or MR2.

Message rate trunk MRT includes party identifying means comprising a test control relay M and a test relay d2. Relay 4! is operated immediately after the first digit dialed at the calling station, in a manner described in Patent 1,823,- 688 to H. Hovland, September 15, 1931, to connect test relay 42 to the conductors of the calling line.

In the case of a call initiated at station Pl relay 42 does not operate, due to the fact that no ground is applied to the line L but if the case is initiated at station P2, relay 42 operates in series with the ringer of that station and closes a circuit for relay 43 which thereupon locks thus preparing a circuit to cause actuation of the message register MR2 corresponding to station P2 when the called station answers.

A pulse supply circuit PS common to the exchangeis shown at the lower right of the drawing and comprises a source of alternating current, l0, 110-volt cycles for example, connected to the primary winding of a transformer T, two

three-element gas-filled tubes I I and I2 having their anodes connected to opposite ends of the secondary Winding of the transformer, which is connected to ground at its mid-point, and four rectifying tubes I3, I i, I and I3, the anodes of tubes I3 and I4 being connected to the anodes of tubes II and I 2, respectively, the cathodes of tubes I3 and I5 being connected together and to the front contact of relay 43, the cathodes of tubes I4 and It also being connected together and to the back or normal contacts of relay 43 and the anodes of tubes I5 and It being connected together and to a positive potential grounded source 36 of direct current having a voltage substantially equal to the drop between the anode and cathode of either tube I5 or Iii. The cathode of tube II is connected to ground through a resistance I? and to the control anode of the tube 2 in the line circuit LC in series with a current limiting resistance I8, and the cathode of tube I2 in a corresponding manner is connected to ground in series with a resistance I9 and to the control anode of tube I in series with resistance 20.

The operation of the circuit of the invention is as follows:

Assuming station PI calls, line relay 3!] in operating causes the line finder LE to come to rest on the line L in a Well-known manner. Immediately after the first digit of the called number has been dialed, test control relay lI operates in the manner disclosed in the before-mentioned Patent 1,823,688 to connect test relay 52 to the conductors of the line, and, as station PI when calling does not connect ground to the line, relay 42 will not operate. As relay 2 does not operate at this time, relay 13 remains released and its normal or back contacts remain closed.

Succeeding digit pulses of the called number causes selector SI. and connector 02, to extend the call to the desired subscribers line LX; whereupon, the bell at the called station is rung and when the subscriber removes hi receiver from the switchhook, the connector, in accordance with well-known practice, reverses the cur rent through the windings of relay 50 to cause its operation.

Relay 50, when operated, closes a circuit to energize start magnet M of a timing mechanism TA which may be individual to trunk MRT or common to a plurality of similar trunks. As soon as the timing mechanism moves out of normal position, in response to operation of relay 56, contacts 52 are closed to operate relay 45. Prior to operation of relay to, the connection between the calling and called lines has been maintained over sleeve conductor 33 by ground in the connector 02, which holding circuit includes contacts 49 of relay 46.

Alternatin current source It alternately causes the two ends of the secondary winding of transformer T to assume a positive potential and therefore for one-half cycle of the source, the control anode of tube I 2 and the anode of rectifier tube It will both be at positive potential and for the other half cycle the control anode of tube I I and anode of rectifier tube I3 will be positive.

When the control anode of tube I2 is positive, that tube will ionize and discharge current will flow between the corresponding main anode and cathode in series with resistanc I 9 and when the control anode of tube 55 is positive, a similar discharge current will flow through resistance H.

The control gap of tube I in the line circuit is connected across resistance is in the discharge circuit of tube I2 and the control gap of tube 2 is similarly connected across resistance I1 in the discharge circuit of tube I I. Consequently. when current flows in resistance I 9 during the half cycle when the anode of tube I2 i positive, tube I in the line circuit will be ionized due to the potential drop in resistance I9 thus priming or conditionin tube I for operation when its anode becomes positive. Similarly, tube 2 will be ionized in condition for operation when tube I I fires due to the potential drop in resistance I'I.

When the phase of the source III is such that tube I2 is discharging, tube I in the line circuit is conditioned for operation. It will be noted that rectifier tube I4 is poled in such a direction that a path for a current flow exists from the secondary winding of the transformer T, anode to the cathode of the tube I 4 and over conductor 2i to the back contact of relay 43 and when the phase of the supply current is reversed, a similar path exists through tube I3 and over conductor 22 to the front contact of relay 43.

Now when relay 46 is operated during the interval contacts 52 of the timing mechanism are closed if, as assumed, station PI is calling which does not cause the operation of relay 43, a positive pulse of direct current occurring every other half wave of the supply source is connected to the sleeve conductor of the trunk MRT in a circuit from the secondary winding of the transformer T, rectifier M, conductor ZI, back or normal contact of relay 43, contact 23 of relay 46, sleeve wiper of the line finder, conductor 24, windings of message register control relays I and 2 in parallel to the anodes of tubes I and 2. During this half cycle of the supply source tube I in the line circuit, as previously described, is ionized and conditioned for operation, and it therefore breaks down and discharges to ground thus operating relay MRCI which in turn causes operation of message register MRI. Relays MRCI and MRC2 each have a second winding which is shortcircuitecl when the relay operates to give the relay a slow-release characteristic and prevents more than one operation of the register during the interval relay 46 is operated.

If station P2 calls, relay 42 followed by relay 43 are operated, the latter locking itself to ground. When the called subscriber answers, thus operating relay 5U, relay 46 connects the sleeve con ductor from the line circuit over its contact 23, front contacts of relay 43, and conductor 22 to rectifier I3. If tube 2 of the line circuit is enabled, i. e., ionized, at this time in synchronism with the pulses transmitted by tube I3, message register MR2 is operated once during the interval contact 52 of the timing mechanism is closed.

Due to the opposing connection of rectifier tubes I3, I5, and I4, I6, when either tube I3 or I 4 conducts, the respective opposin tube I5 or I6 is not conducting, but conversely when I3 or I4 is in a non-conducting condition, its respective opposing tube conducts. Due to the proper selection of a direct current potential for the source 36, which is substantially equal to the drop through the tube I5 or I6, 20 volts for example, conductors 2| and 22 will be at substantially ground potential during half the cycle of the supply source Ill. This ground potential is effective, when contacts 49 of relay 46 are opened, to hold the cut-off relay 35 operated and th connection maintained during the interval between metering pulses. Relay 35 is held operated during application of metering impulses by the difference between the exchange battery potential (48 volts) at the relay'and the positivevoltage supplied by rectifier tube I3 or M which intro duce a 20-volt drop in the voltage supplied by transformer T.

The present arrangement, shown for message register operation, is also applicab1e, with only minor circuit modifications, for use in controlling collection or returnof coins deposited at coin box paystations which modification will be obvious and understood by'those skilled in the art.

IV hat is claimed is:

1. In a selective message register system, a telephone line, twomessage registers associated with said line, a pair of gas-filled discharge tubes each having at least two mutually spaced electrodes, one or which electrodes is an anode, each of said tubes individualized to one of the registers associated with said line, a source of alternating current; means for supplying full cycles fromsaidsource to other corresponding electrodes of said tubes 180'degrees out of phase with each other, means for deriving two successive positive potential impulses from each complete cycle of said alternating current, switching means for selectively applying one or the other of said two successive impulses to the anodes of said tubes to cause the discharge of the tube of said pair which is properly conditioned for discharge by the simultaneous application to its said other electrode of the half cycle of said source of the proper to cause discharge of said tube, and a difierent one of said two message registers associated with each of said tubes and operable in response to the discharge thereof.

2. In a selective message register system, a telephone line, two message registers associated with said line, a pair of gas-filled discharge tubes each having at least two mutually spaced electrodes, one of which electrodes is an anode, each of said tubes individualized to one of the registers associated with said line, a source of alternating current, means for supplying full cycles from said source to other corresponding electrodes of said tubes 180 degrees out of phase with each other, means for deriving two successive positive potential half cycles from each complete cycle of said alternating current, switching means for selectively applying one or the other of said two successive half cycles to the anodes of said tubes to cause the discharge of the tube of 5 said pair which is properly conditioned for discharge by the simultaneous application to its said other electrode of the half cycle of said source of the proper polarity to cause discharge of said tube, and a different one of said two message registers associated with each of said tubes and operable in response to the discharge thereof.

3. The combination in a selective system of an impulse conductor, a pair of discharge tubes, a source of alternating current voltage, circuit means for connecting said source to said pair of tubes in such a manner as to cause the discharge of one of said tubes when the wave of said source reaches a definite value in a positive direction and the discharge of the other tube when said wave reaches a definite value in a negative direction, a discharge circuit for each tube including a resistance element through which current flows following the discharge of its associated tube, a pair of current responsive devices to be selectively controlled, a second pair of discharge tubes each having an anode, a cathode and a control electrode, means for connecting each current responsive device, in series with the anode circuit of a difierent one of said second tubes, to said impolarity pulseconductor, circuit means for connecting? the cathode and controlelectrodeof each-of=saidi second pair of tubes across a different one'of said" resistances to cause said second pair of tubes to be alternately ionized in accordance with the change in phase of said source, means forde'- riving a positive potential impulse during: each half cycle of said alternating current source; and means for applying positive potential impulsesderived from either half cycle to theimpulse-conductor, to the exclusion of impulses derived from the other half cycle, to cause conductive discharge of the one of said second pair of tubes which is ionized at the'time, and the consequentresponse of the respective serially connecteddevice.

4. In a telephone system, a two-party line; a pair or message register control relays, a sleeveconductor, a first pair of gas-filled discharge tubes each having an anode, a cathode anda control electrode, a connection between each-anode and said sleeve conductor, each connection serially including a different one of said control relays, a source of alternating current, a second pair of discharge tubes, circuit means for connecting said alternating current source to said second pair of tubes to cause one tube to discharge when the potential of said source reaches a predetermined positive value and to cause the other tube to discharge when the source potential reaches a predetermined negative value, a resistance in the discharge circuit of each of said second pair of tubes and through which current flows during the discharge of the associated tube, means connecting the control electrode and cathode of one of the first pair of tubes across the resistance in the discharge circuit of one of the second pair of tubes and the control electrode and cathode of the other of the first pair of tubes across the resistance in the discharge circuit of the other of the second pair of tubes whereby the voltage across the resistance associated with the discharging tube of the second pair causes ionization of the associated tube of the first pair, other means for deriving two successive positive potential impulses from each complete cycle of said alternating wave and switching means for selectively connecting one or the other of said two successive impulses to said sleeve conductor to cause discharge of the ionized tube of the first pair and consequent operation of the respective register control relay.

5. In a telephone system, a two-party line, a pair of message register control relay-s, a sleeve conductor, a first pair of gas-filled discharge tubes each having an anode, a cathode and a control electrode, a connection between each anode and said sleeve conductor, each connection serially including a difierent one or said control relays, a source of alternating current, a second pair of discharge tubes, circuit means for connecting said alternating current source to said second pair of tubes to cause one tube to discharge when the potential of said source reaches a predetermined positive value and to cause the other tube to discharge when the source potential reaches a predetermined negative value, a resistance in the discharge circuit of each of said second pair of tubes and through which current flows during the discharge of the associated tube, means connecting the control electrode and cathode of one of the first pair of tubes across the resistance in the discharge circuit of one of the second pair of tubes and the control electrode and cathode of the other of the first pair of tubes across the resi-stance in the discharge circuit of the other of the second pair of tubes whereby the voltage across the resistance associated with the discharging tube of the second pair causes ionization of the associated tube of the first pair, other means for deriving two successive positive potential impulses from each complete cycle of said alternating wave and switching means for selectively connecting one or the other of said two successive impulses to said sleeve conductor to cause discharge of the ionized tube of the first pair and consequent operation of the respective register control relay, a cut-ofi relay in series with a grounded negative source of direct current connected to said sleeve conductor and maintained operated by ground connected to said conductor during progress of a call over said line, said ground disconnected during the interval registration impulses are applied to said conductor, and other means for maintaining said sleeve conductor at ground potential, to hold said cut-off relay operated, when the registration impulses REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,322,330 Vroom June 22, 1943 2,332,015 Scheer Oct. 19, 1943 2,391,532 Wilmotte Dec. 25, 1945 2,424,243 Lowell July 22, 1947 

